Final answer:
Parental-investment theory stresses the evolutionary basis of many aspects of parental behavior. It explains why parents invest different amounts of time, energy, and resources into their offspring.
Step-by-step explanation:
Parental-investment theory stresses the evolutionary basis of many aspects of parental behavior. According to this theory, parental behavior is shaped by the need to ensure the survival and success of their offspring, in order to pass on their genes to future generations. This theory explains why parents invest different amounts of time, energy, and resources into their offspring, and why certain parental behaviors are more common in some species than others.